Bonding adhesive for an abrasive article such as sandpaper



Patented May 28, 1940 UNITED STATES PATENT OFFICE BONDING ADHESIVE FORAN ABRASIVE ARTICLE SUCH AS SANDPAPER sota No Drawing. ApplicationSeptember 11, 1930, Serial No. 481,351

20 Claim.s. (Cl. 260-29) posite structures of which forms of abrasivesuch as what is commonly known as sandpaper is an example.

Although I hereinafter disclose the practice of my invention inconnection with abrasives such as sandpaper, it will be understood thatmy invention of certain features thereof has a wider field of utility.

Composite structures of the abrasive type, such as sand-paper or emerycloth, comprise generally (a) a base of sheet material which may befelted as in the case of paper or woven as in the case of cloth; (1:) amore or less finely comminuted resistant material having abradingproperties such as garnet or corundum and (c) a binder generally in theform of the glue which serves to bind theabrasive to the base.

Where I have attempted to make abrasive products suitable for liquidsanding operation and having a high order of flexibility in which thebinding ingredients for the abrasive particles include the waterrepellant properties of materials of the resinous type or resin-varnishtype including 'drying oils, the new materials being of extremelycomplex, arbitrary nature or having varying properties due to themethods used for their production, derivation or extraction from v theirnatural sources, these materials have been found. to give non-uniformresults or results ous or drying oil type above referred to is of suchcomplex character that when used with thinners of solvents therefor tosaturate, impregnate or otherwise coat the base or backing, uniformityis not a certainty and such factors as porosity of paper, ability to wetthe abrasive due to the nature of its surface, etc., will give markednonuniform results in the final product.

The present invention contemplates the provision of an abrasive articlein the nature of sandpaper and a new binding material susceptible ofapplication to the materials entering into an abrasive article, such asthe base or backing, either cloth or paper, and the abrasive grit orlayer, whether of the natural, electro-furnace type, vitreous type orbaked type abrasive and 5 assure uniformity of results so far as theweight of the article is concerned, its deterioration factor throughoutperiods of storage, flexibility and resistance to mechanical agencieswhen used in dry or wet abrading operations and which properties may beobtained with great facility, without special care and permits theutilization of standard equipment in the abrasive art, such as sand- P pIn its preferred form, my invention contemplates the provision of anabrasive article in the nature of sandpaper including the reaction,condensation or polymerization of products resulting when polyhydricalcohols or their anhydrides or similar compounds or when polyhydricacids or their anhydrides or similar compounds are used as components,together with another compound or compounds, with or without a modifyingagent or agents to produce such compounds as commonly are calledsynthetic resins or condensation products and one which functions moreefliciently than any other prior binder known to me; the provision of anabrasive article having a binder characterized by its uniformity ofphysical and chemical properties whereby any desired and predetermineddegree of flexibility may be imparted to the abrasive article; theprovision of an abrasive article having a binder characterized byextensibility and compressibility to accommodate itself to flexion ofthe base without permanent distortion, deleterious disintegration due toatmospheric conditions, temperature changes or actinic exposure; theprovisions of an abrasive article having a' binder of great tensilestrength and flexibility resulting from the ability of the binder totenaciously attach itself to materials of various surfacecharacteristics, such as natural or artificial abrasive particles andthe porous base or backing and obtain uniformity of the compositearticle as to flexibility, abrasive resistance, and which may beconducted with an exercise of a low order of care; the provision of anabrasive article having a binder which is resistant to liquids used insanding operations or finishing operations, whether water, organicsolvents or inorganic materials, such as strong acids or alkalis; theprovision of an abrasive article having a binder which may be attachedto an organic base or backing material, such as paper and which may befurther matured to its final stage -cluding a binder which may bemodified for application to a base or backing having various porosityfactors characteristic in the properties of paper when sized or unsized,or thick or thin sheets thereof and which requires no material I changeto accommodate itself to abrasive particles useful for various purposes,.as may be occasioned by adopting natural or artificial abrasive; theprovision of an abrasive article including a binder which may be used inany point in the composite structure of the abrasive article such as thesize, back size or pre-size and a bond and sand or grit size, withoutmaterial modification of the binder for the various purposes enumerated.

In the employment of my present invention for the production ofsandpaper and the like (which I cite for purposes of example) I use asthe base such a sheet of material (a woven web of material or adeposited or felted web of material such as paper) as will havepredetermined porosity factors and serve conveniently for the employmentcontemplated, and as the abrasive I use such comminuted material as maybe classified as natural abrasives, such as flint, garnet or corundum,or artificial abrasives such as of the character used for makingargillaceous refractories or electro-furnace products, as'siliconcarbide or the like of various grades and sizes, surface character,etc., as is similarly adapted to perform the function in view.

It is most desirable that the binder utilized have the functions andcharacteristics not only of great mechanical strength, includingtoughness,

resistance to tensile and shearing strains and of great bindingstrength, including adhesiveness and tenacity and ability to wetabrasive particles under all conditions of surface contour, but alsothat it be moisture resistant, unafiected by a large number of liquidswhich may be used in liquid sanding operations, easily worked, made ofmaterials easily obtainable on the market, of definite chemicalcomposition and uniformity, inexpensively and facilely worked andapplied and when used with a base material which is penetrable,penetrative of such base as to form a strong union therewith and,furthermore, when built up into a plural layered composite article,retain a predetermined flexibility, free from deteriorating factors suchas changes in temperature,atmospheric conditions or actinic exposure.

I have discovered that resinous materials including a polyhydricsubstance are preferable not only to gum, gum resins, hardened oils, butto phenolic condensation products for purposes contemplated by me, andparticularly resins having as their base polyhydric substances or theiranhydrides, which are peculiarly adapted for my ends for a number ofreasons, including that their characteristics can not only be bettercontrolled than in the case of the other materials first enumerated, butthat batches of the desired characteristics can be readily reduplicatedand the desired properties imparted to the composite article with alarge variation in the basic ingredients, such as the backing and theabrasive particles, I have found that certain materials, such aspolyhydric alcohols or polyhydric acids are available to give byinteractions, condensation or polymerization a material which ispreferred by me as a major constituent of the binder, that is, as bestto attain the desired ends, viewed from certain aspects.

In carrying out my invention, in order that the resinous material may beof a known quantity and of known quality, and of predetermined ageingproperties, I prefer to react, condense or polymerize polyhydricalcohols or their anhydrides or similar compounds or polyhydric acids ortheir anhydrides or similar compounds, used as components, together, orwith another compound or compounds with which they are adapted to react,condense or polymerize to resinify, and may be further suitably modifiedby agents to impart additional properties of flexibility andpenetrability of the base or backing or for adhesively binding thevarious abrasive particles. The treatment to which I subject these basicmaterials results in a resinifled composition, in certain aspectspossessing novelty, uniformity and physical properties peculiarly usefulin the sheeted abrasive art, such as freedom from gumminess or tendencyto clog during intensive abrasive operations.

In producing the desired binder, I employ a number of alternativemethods, each of which appears to have certain favorable characteristicsand advantages. One method which has given very good results will now bedescribed in some detail as-- Example No. 1

Grams Polyglycerine 100 Phthalic anhydride 200 are mixed together andheld for a short time at a temperature of 100 to 110 C. The resultingproduct will produce a resinous mass which may be heated for directapplication to form a size or bond or thinned for sizing. This materialmay be used as a paper size, sandsize, back-size, a hinder or bond forthe abrasive particles. The consistency may be modified to take care ofsuch components as porosity and penerativeness of the backsize. Forinstance, with paper having a low porosity and high penetrativeproperties I may heat the resin for only thirty minutes at 110 C. anduse 35% thinners of such a nature as 50% benzol and 50% acetone togetherwith 65% resin. On the other hand, for a paper having a high porosityand low penetrative properties I may heat the resin for, say, threehours at 110 C. and use 45% thinners and 5% resin for producingpre-size.It is evident from this that by varying the quantity of condensationand/or polymerization of the resin and varying the quantity of thinnersI may be able to takecare of such factors as porosity andpenetrativeness of the base. After separation of the solvent, if such isused, the resin may be matured by heating at a temperature of from to C.for a period of 19 hours or where the material is applied in fairly thinlayers, a higher temperature for a shorter period of time may beutilized to set the final product.

In this type of resin particularly, this condensation resin may becombined with modifying agents such as various drying, semi-drying andnon-drying oils. Though the example has been given with phthalicanhydride as the single aromatic acid, this.may be combined with analiphatic acid, such as oleic, butyric, succinic, citric, benzoic,malic, glutaric, suberic, camphoric, adipic, linoleic and eleostearicand others.

Though I have mentioned above glycerine as the polyhydric compound,under some conditions though not as preferable, glycol and otherpolytreatment afterward. For certain purposes this hydric alcohols maybe used, such as Dihydroxyethane 1-2 Dihydroxypropane 1-2Dihydroxypropane 1-3 Trihydroxypropane 1-2-3 Grams Resin as produced inExample I 100 Chinese wood oil 15 are mixed and held at a temperature ofabout 110 C. for about 5 minutes, with continued stirring. This resinousmaterial may now be thinned in accordance with the proportionsenumerated above to vary the consistency of the solution to take care ofthe porosity of the base or backing and the size and character of theabrasive particles. After evaporation of the vehicle or solvent, thebase with its residue may be heated to mature the same temperatures from85 C. to 90 C. for a period of about 19 hours. In the example given,other oils which may be used are the various drying, semi-drying andnon-drying oils, uch as wood oil, linseed oil, castor oil, cottonseedoil, rape seed oil and soya bean oil, within limits approximating 15% to50% of the resin, with the modification as to the quantity dependingupon the characteristics of the various oils to impart the desiredflexibility to the resinous binder upon the base or backing. These oilsor modifying agents act in the nature of softening agents or emolients.Gelatinizing substances, such as camphor substitutes and the heavier,less volatile solvents for the resins may also be included. Of thegelatinizing agents and high boiling solvents there may be used thegelatinizing agents or solvents used in connection with cllulosiccompounds, such as nitrocellulose, cellulose ethers and esters. Thecamphor substitutes or gelatinizing agents referred to are particularlydesirable in that they are volatile, which leave the binder or resinousbase free from gumminess tending to accumulate and clog the sandpaper bythe abraded particles removed in the abrading operations.

The previous examples produce materials which are usually to bepreferred as a binder, sandsize or backsize. I have found it possible toproduce a material admirably adapted for a paper treatment or centersize by the following example:

Example No. III

Grams Diethyleneglycol l 100 Phthalic anhydride 200 are mixed togetherand held for from 3 to 20 hours at 110 C. The resulting product is aresinous material which at high temperatures is quite liquid, but atordinary temperatures is a very tacky, slightly plastic resin. Thisresin may be put into solution with such solvents as 50% benzol and 50%alcohol in proportions of 35% resin and 65% solvents. This material maybe used as a centersize or presize for paper. The paper may or may notbe subjected to a baking Example N0. IV

Grams Phenol 100 Glycerol 70 Concentrated sulfuric acid are refluxed atatemperature between 160 and 190 C. until -35 g. of water have beendistilled over. The sulfuric acid is neutralized with barium carbonate.Any other basic material, such as, for instance, hydroxides, carbonatesor similar compounds of the alkali metals or alkali earths, aresuitable. Calcium oxide may further be mentioned as another suitableneutralizing agent. This material may be used as a paper size, sandsize,backsize, a binder or bond for abrasive particles. The consistency maybe modified to take care of such components as porosity andpenetratlveness of the base and backing. For instance, for a materialhaving a low porosity and low penetrative properties I may distill offonly 32 g. of water and use 35% thinners such as benzol together with65% resin for the production of a 'presize: while for a paper having ahigh porosity and high penetrative properties I may distill off 37 g. ofwater and use 45% thinners and 55% resin for producing the same actionas a presize. I may use as solvents for this type of resin such solventsas acetone, alcohol, amyl-acetate or cellosolve or mixtures of thesesolvents.

To produce a binder, the solutions of a resin may be modified so that35% to 15% of solvents may be added to 65% to 85% of resin. Thesepercentages may be varied as well as the solvent to take care of thesize of fineness of the grit and its character. sive, of a fineness of280, the preferred proportions of resin to solvent are 75 to 25, inwhich the solvent is preferably 25. With coarser abrasive having afineness of 220 mesh, I may use a binder mixture having resin 80%,solvent 20%. Under certain conditions it will be observed that theresinous material may be made to partial completeness and of a fluiditysuflicient to be used as a bond or penetrative sizing coat directly.

Where the resinous material as above described, with or without thesolvent is used for a fabric size or bond or sand size, it is preferableto set the resinous residue by heat or, where a solvent or thinner hasbeen used, to apply the resinous material, these solvents may berecovered by suitable recovery apparatus. The resinous material, whetherapplied with a thinner or directly, is matured by heat in accordancewith the desired flexibility, hardness and insolubility in varioussolvents. The higher the temperature, the more infusible and insolublewill be the final product for a given time of baking. Also, with thehigh- Thus using garnet as the abraer temperatures, a change to thefinal product takes place more readily. With a mixture as abovedescribed in Example 1, a temperature from to C. for 15 hours willproduce a change to the final stage of high infusibility; a

temperature from 180 to 200 C. for 5 to 10 hours will procureapproximately the same result. However, where the resinous material isapplied in relatively thin layers and a highly bibulous type of paper isused, for purposes of preventing scorching of the paper and by reason ofthe thinness of the layer of resinous material, a high temperature maybe used to quickly mature the resin to the final stage Without scorchingthe paper. Certain additional flexibility may be imparted to theresinous material by the addition of various oils, amongst which theremay be enumerated wood oil, linseed oil, castor oil, cottonseed oil,rape seed oil, soya bean oil, as well as other semi-drying andnon-drying oils. These may be added in proportions as follows:

7 Per cent Final resin Oil 20 The resinous solutions or the resin itselfat the intermediate stage are best applied with the aid of pressurerolls and, additionally the final stage may be effected by heating underpressure. Also, though I have described the application of the resinousmaterial for penetration purposes or coating in the form of a solutionof the resin, or of the resin itself at the intermediate stage, itsapplication may be facilitated by preliminarily wetting the abrasive orthe backing with a solvent for the resin, eliminating the solvent at thefinal maturing step of the resin.

A modification of Example I may be practiced as follows:

Example No. V

Grams Glycerine Phthalic anhydride 200 are heated to about 185 C. untilthe evolution of water has ceased. This product is mixed with about g.of Chinese wood oil and heated in agent by precipitation with benzol,the remaining product is admirably suitable for the uses described inconnection with the Examples I and. II, where solution is ,eflected bysolvents such as ethyl alcohol and benzene in proportions of 50% ofalcohol to 50% of benzene. Other dispersion agents may be used asfollows: benzyl acetate, nitrobenzene, toluidine, benzyl alcohol,cresol, aniline, glycol diacetate, phenol-hydrazine and ortho-cresolbenzoate. This material may be thinned to the consistency for producingbest results for penetration of a porous base or backing, such as paper,and for wetting and tenaciously binding abrasive particles, dependingupon the fineness and size of the abrasive particles and their generalsurface condition, due to its inherent characteristics.

For a paper of the character previously deseribed in Examples I and H, Imay thin the resin above described with about 30% of a solvent such as50% alcohol and 50% benzene. After removal of the solvent, this resinmay be matured or set by heat at a temperature of from 80 to 100 C. fora period of 19 hours. A higher temperature and a lower time of exposuremay be utilized where the resinous material is spread in very thinlayers. As recited in the case of Examples I and II, the otherpolyhydric materials may be used with a certain amount of success.

Example No. VI

Grams Phthalic anhydride 200 Glycerol 100 are heated together at 100 C.for one hour. The resultant resin is dissolved in 300, g. of furfural,after which 300 g. of cresol are added. 10 g. of an alcoholic solutionof hydrochloric acid serves as a catalyst for accelerating the hardeningof this resin. This resin instead of requiring 20 hours to harden as isthe case in Example IV required about one-half as long, or 10 hours inwhich to harden. This resin may be modified by various products asoutlined in Examples I and II to take care of porosity, penetrativenessor particle size.

Example No. VII

This procedure will produce a slightly different resin by reactingtogether 200 g. of phthalic anhydride and 100 g. of glycerol as outlinedin Example VI. To this I add 600 g. of a resin produced by heating GramsFurfural 300 Cresol 300 with 10 g. of an alcoholic solution ofhydrochloric acid until the resin begins to polymerize and body at aboutthe desired consistency. At this stage I add sufficient base in the formof sodium hydroxide, barium hydroxide or similar compound to neutralizethe hydrochloric acid used as a catalyst. These two resins I then mixtogether and use as outlined in Example VI.

I may, on the other hand, introduce all of the components at one time,reacting them together and produce a resin which is different in itsproperties from that produced by either of the preceding methods. Forinstance;

Example N0. VIII Grams Phthalic anhydride 200 Glycerol 100 Furfural 200Cresol 300 25 g. alcoholic solution of hydrochloric acid as catalyst. Iheat this, mix until the desired body is produced, at which time I addsuflicient quantity of base to neutralize all but 5 g. of the alcoholicsolution of hydrochloric acid. This resin may also be used in the samemanner as Example VI.

Although in Examples VI, VII, and VIII the proportions and constitutentshave been kept identical in order to illustrate the different methodswhereby the same components may be reacted together, it is to beunderstood that other materials may be reacted with a polyhydricsubstance in a similar manner.

Having thus described my invention and illus- 75 trated itsuse, what Iclaim as new and desire to secure by Letters Patent is- 1. A flexibleadhesive coating material composition for coating and penetrating afibrous base material in the nature of paper, cloth or the like for agrit or layer of abrasive particles to form therewith an article in thenature of flexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrading operations, the said adhesive comprisinga resinifled condensation product of a polyhydric compound and anaromatic acid and a flexibilizing and gelatinizing compound.

. 2. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles to form therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric compound and an aromatic acid and a flexibilizing andgelatinizing compound, said product being dispersed in a volatilethinner.

3. A flexible adhesive coating material composition for coating andpenetrating a base coat in the nature of paper for a grit or layer ofabrasive particles to form therewith an article in the nature of aflexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrasive operations, said adhesive comprising aresinifled condensation product of a polyhydric compound and an aromaticacid in a volatile thinner in the proportions of 15-45% of the volatilethinner to 85-55% of the resinifled product,

and a flexibilizing and gelatinizing compound.

4. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles to form therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric compound and an aromatic acid and a flexibilizing andgelatinizing compound, the latter being employed in quantitiescomprising 15 to 50% of the resulting resinifled product.

5. A flexible adhesive coating material composition for coating andpenetrating a base coat in the nature of paper for a grit or layer ofabrasive particles to form therewith an article in the nature of aflexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrasive operations, said adhesive comprising aresinifled condensation product of a polyhydric compound and an aromaticacid in a volatile thinner in the proportions of 15-45% of the volatilethinner to 85-55% of the resinifled product, and a flexibilizing andgelatinizing compound in quantities comprising 15% to 50% of thegelatinizing and flexibilizing agent to the quantity of resinifledproduct.

6. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles forming therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, the.said adhesive comprising a resinifled condensationpr'oduct of apolyhydric alcohol, a polybasic aromatic acid, and a reactiveflexibilizing and gelatinizing agent comprising an unsaturated higherfatty acid.

7. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles forming therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading'operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric alcohol, a polybasic aromatic acid, and a reactiveflexibilizing and gelatinizing agent comprising an unsaturated higherfatty acid, said condensation roduct being dispersed in a volatilethinner.

8. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or lawer of abrasive particles forming therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric compound and an aromatic acid and a reactive flexibilizingand gelatinizing agent comprising at least one material from the groupconsisting of linoleic acid, oleic acid, eleostearic acid, camphoricacid and succinic acid.

9. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles to form therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric compound and an aromatic acid and a flexibilizing andgelatinizing agent comprising linoleic acid, thereby to provide a coatedarticle in which the resinous material will cure without injury to thefibrous backing.

10. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles forming therewith anarticle in the. nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric compound and an aromatic acid and a flexibilizing andgelatinizing agent comprising eleostearic acid, thereby to provide acoated article in which the resinous material cures without injury tothe'fibrous back- 11. A flexible adhesive coating material compositionfor coating and penetrating a fibrous base material in the nature ofpaper, cloth or the like for a grit or layer of abrasive particlesforming therewith an article in the nature of flexible tinizing agentincluding a drying oil and a drying oil acid. I

13. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles to form therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a resinifled condensation product of apolyhydric compound and an aromatic acid and a flexibilizing andgelatizing agent comprising an unsaturated higher fatty acid.

14. A flexible adhesive coating material compo- Y sition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles to form therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a mixed resinifled condensation product of apolybasic acid, a glycerol, an aldehyde and a phenol and a gelatinizingagent.

15. A flexible adhesive coating material composition for coating andpenetrating a base coat in the nature of paper for a grit or layer ofabrasive particles to form therewith an article in the nature of aflexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrasive operations, said adhesive comprising amixed resinifled condensation product of a polybasic acid, a glycerol,an aldehyde and a phenol, in a volatile thinner, and a gelatinizingagent.

16. A flexible adhesive coating material composition for coating andpenetrating a fibrous base material in the nature of paper, cloth or thelike for a grit or layer of abrasive particles to form therewith anarticle in the nature of flexible waterproof sandpaper having lowgumming and clogging characteristics during abrading operations, thesaid adhesive comprising a mixed resinifled condensation product ofphthalic anhydride,

glycerol, an aldehyde and a phenol and a gelatinizing agent.

17. A flexible adhesive coating material composition for coating andpenetrating a base coat in the nature of paper for a grit or layer ofabrasive particles to form therewith an article in the nature of aflexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrasive operations, said adhesive comprising amixed resinifled condensation product of phthalic anhydride, glycerol,furfural and cresol in a volatile thinner, and a gelatinizing agent.

18. A flexible adhesive coating composition for coating and penetratinga fibrous base material in the nature of paper, cloth or the like for agrit or layer of abrasive particles forming therewith an article in thenature of flexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrading operations, the said adhesivecomposition comprising a resinifled condensation product of a polyhydricalcohol, a polybasic acid, and a reactive flexibilizing and gelatinizingagentcomprising an unsaturated higher fatty acid, and of an aldehyde anda phenol.

19. A flexible adhesive coating composition for coating and penetratinga fibrous base material in the nature of paper, cloth or the like for agrit or layer of abrasive particles forming therewith an article 'in thenature of flexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrading operations, the said adhesivecomposition comprising a resinifled condensation product of a polyhydricalcohol, a polybasic aromatic acid, and a reactive flexibilizing andgelatinizing agent comprising an unsaturated higher fatty acid, and ofan aldehyde and a phenol.

20. A flexible adhesive coating composition for coating and penetratinga fibrous base material in the nature of paper, cloth or the like for alayer of grits or abrasive particles forming therewith an article in thenature of flexible waterproof sandpaper having low gumming and cloggingcharacteristics during abrading operations, the said adhesivecomposition comprising a resinifled condensation product of a polybasicacid, a polyhydric alcohol, an aldehyde, a phenol and a reactiveflexibilizing and gelatinizing agent comprising an unsaturated higherfatty acid.

DURWARD OGDEN GUTH.

, CERTIFICATE OF CORRECTION. Patent No. 2,20'2T765. May 23, 191p;

' DURWARD OGDEN GU'IH. It is hereby certified that error' appears in theabove numbered patent requiring correction as follows In the headingtothe printed specification,

- lines 8. and 9 thereof, for "Application September 11, 1950, SerialNo.-

M31551" read "Original application March 11;, 1929, Serial No. 3l7,159." Divided and'this application September 11,1950, Serial No.h8l,551--; and" page 1,'fir st column, line 1, before the words "Thepresent.invention",in-. sort the following paragraph p This applicationis a'ldivision of application Serial No.

5l 7,159, filed Manoh 11;, 1929.

t, L J I and that the said Letters Patent should be read withthisioorrection therein that the same may conformto the record of thecase in the Patent Office.

Signed and sealed this 10th day of September, A. D. 191w.

v Leslie Frazer (Seal) Acting Commissioner of iatents.

